The main objective of this project is to develop improved statistical techniques for using data from animal carcinogenicity tests conducted at high dose levels to estimate long-term human risk from chemical carcinogens at very low dose levels. Current research efforts are focusing on a variety of issues such as competing risk analysis, species-to-species extrapolation, the incorporation of pharmacokinetics in low dose risk estimation, and cancer bioassay design. In addition mathematical models for the genetic effects of radiation have also been considered.